Many compounds having a pyridonecarboxylic acid moiety re known to be useful as antibacterials. For example, a series of novel quinolone antibacterials appears in PCT Application No. PCT/JP96/02710, published as WO97/11068 on Mar. 27, 1997 and issued in United States as U.S. Pat. No. 5,998,436 on Dec. 7, 1999, U.S. Pat. No. 6,133,284 on Oct. 17, 2000, and U.S. Pat. No. 6,156,903 on Dec. 5, 2000.
There is therefore an existing need for processes for making these compounds in large scale quantities.